Silk gland specific cDNAs from Galleria mellonella L.

Z̆urovec, Michal; Sehnal, František; Scheller, Klaus; Kumaran, A. Krishna

doi:10.1016/0965-1748(92)90100-s

Cited by 25 publications

(32 citation statements)

References 22 publications

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“…The culture was carried out under gentle shaking for 24 h at 27°C; the medium was replaced at 12 h. In a few cases, cycloheximide (40 g/ml) or anisomycin (10 g/ml), which efficiently inhibited protein synthesis in explanted silk glands (27), were dissolved in the medium just before use. 4 plaques of the silk gland-specific cDNA library prepared previously (14). All three cDNA clones, which were isolated in the first screen, contained an open reading frame that included appropriate amino acid sequence.…”

Section: Methodsmentioning

confidence: 99%

“…Isolation of cDNA Clones and Nucleotide Sequencing-Galleria silk gland cDNA library in gt10 (14) was screened with degenerate 30-mer oligoprobe that was derived from the N-terminal sequences of the 23-kDa silk proteins. The probe (10 pmol) was end-labeled with 50 Ci of [␥-32 P]ATP; free nucleotides were removed by chromatography on Sephadex G-25.…”

Section: Methodsmentioning

confidence: 99%

“…A lower amino acid conservation, but a similar tandem distribution of the amino acid repeats, and virtually identical gene organization were found in the H-fibroin gene. 2 Two sericin genes, resembling Ser1 and Ser2 of Bombyx, were identified in Galleria as MSG-specific cDNAs, which were partially sequenced (14).…”

mentioning

confidence: 99%

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Identification of a Novel Type of Silk Protein and Regulation of Its Expression

Z̆urovec¹,

Yang²,

Kodrı́k³

et al. 1998

Journal of Biological Chemistry

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The silk of lepidopteran insects has been studied extensively as proteins of two categories: the fibroins, which are produced in the posterior section of silk glands, and the sericins, which are secreted in the middle section. We now describe a third category that is named seroins to accentuate the fact that both the sericin-and the fibroin-producing cells participate in seroin secretion. Using a probe derived from the N-terminal sequences of a 23-kDa components of Galleria mellonella silk, we isolated silk gland-specific cDNA encoding 167 amino acids, of which 17 constitute the signal peptide. The following 14 residues match the N-terminal sequences of the 23-and 22.5-kDa silk proteines. The reaction of these proteins with concanavalin A and the presence of two glycosylation sites in the seroin peptide sequence indicate that seroin is secreted in two forms that both contain a mannose-rich sugar moiety. Seroin is distinguished from other silk proteins by high proline content (34 residues or 20.26% by weight), lack of cysteines, and the presence of two kinds of short amino acid repeats. The seroin gene is expressed in both the posterior and middle silk gland sections. The expression fluctuates during development in correlation with the feeding regime and the changes in hormone titers: seroin mRNA is high in the silk glands of feeding larvae, declines at ecdysis, reaches a maximum during cocoon spinning, and thereafter rapidly drops to an undetectable level. In vivo and in vitro experiments showed that the drop is caused by ecdysteroid hormones and is prevented by juvenile hormones. N-terminal sequencing of several silk proteins of Bombyx mori revealed that the 8-and 13-kDa proteins share 5 or 6 out of 10 identified amino acids with the N terminus of Galleria seroin and obviously represent seroin homologues. The result suggests that seroin-type proteins are a general component of lepidopteran silk.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Identification of a Novel Type of Silk Protein and Regulation of Its Expression

Z̆urovec¹,

Yang²,

Kodrı́k³

et al. 1998

Journal of Biological Chemistry

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“…In a previous study (17), we isolated from the posterior silk gland region of G. mellonella larvae a cDNA clone designated PG-2. Except for a non-repetitive 0.3-kb 3Ј terminus, the clone consisted of repetitive motifs.…”

Section: Nmmentioning

confidence: 99%

“…The silk of the waxmoth, Galleria mellonella, a species distant in evolution from both B. mori and A. pernyi, was assigned to structural group 3 as the tussah silk (13), but partial sequence of the waxmoth H-fibroin did not disclose any regular polyalanine repeats (17). Also, the silk of G. mellonella has different physical properties than tussah silk.…”

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confidence: 99%

Unique Molecular Architecture of Silk Fibroin in the Waxmoth,Galleria mellonella

Z̆urovec

Sehnal

2002

Journal of Biological Chemistry

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Proteins of silk fibers are characterized by reiterations of amino acid repeats. Physical properties of the fiber are determined by the amino acid composition, the complexity of repetitive units, and arrangement of these units into higher order arrays. Except for very short motifs of 6 -10 residues, the length of repetitive units and the number of these units concatenated in higher order assemblies vary in all spider and lepidopteran silks analyzed so far. This paper describes an exceptional silk protein represented by the 500-kDa heavy chain fibroin (H-fibroin) of the waxmoth, Galleria mellonella. Its non-repetitive N-terminal (175 residues) and C-terminal (60 residues) parts, the overall gene organization, and the nucleotide sequence around the TATA box show that it is homologous to the H-fibroins of other Lepidoptera. However, over 95% of the protein consists of highly ordered repetitive structures that are unmatched in other species. The repetitive region includes 11 assemblies AB 1 AB 1 AB 1 AB 2 (AB 2 )AB 2 of remarkably conserved polypeptide repeats A (63 amino acid residues), B 1 (43 residues), and B 2 (18 residues). The repeats contain a high proportion of Gly (31.6%), Ala (23.8%), Ser (18.1%), and of residues with long hydrophobic side chains (16% for Leu, Ile, and Val combined). The presence of the GLGGLG and SSAASAA(AA) motifs suggests formation of pleated ␤-sheets and their stacking into crystallites. Conspicuous conservation of the apolar sequence VIVI followed by DD or ED is interpreted as indicating the importance of hydrophobicity and electrostatic charge in H-fibroin cross-linking. The environment of G. mellonella larvae within bee cultures requires continuous production of silk that must be both strong and elastic. The spectacular arrangement of the repetitive H-fibroin region apparently evolved to meet these requirements.

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Juvenile hormone restores larval pattern of sericin gene transcripts

Yang

Sehnal

Scheller³

1996

Arch. Insect Biochem. Physiol.

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The transcripts of sericin‐type genes MG1 and MG2 accumulate in Galleria mellonella silk glands during feeding and decline during molting. Three MG1 (1.9, 3.2, and 4.2 kb) and two MG2 (dominant 3.4 kb and minor 5.2 kb) transcripts are detectable from the penultimate instar until the end of cocoon spinning. Experiments with isolated larval abdomens showed that the dramatic change in the ratio of 1.9 and 4.2 kb MG1 transcripts in the last larval instar is due to lack of JH. Transient rise of ecdysteroid titre in the wandering larvae (day 5 of the last instar) is associated with appearance of additional MG1 transcripts (10.0, 7.2, and 5.0 kb), while the molt‐inducing ecdysteroid surge on day 7 causes a drop of all transcripts. The drop is prevented and the profile of transcripts is reverted to a larval‐like pattern when the last instar larvae are treated with a juvenoid. The profile of MG1 transcripts is affected only when the treatment is applied prior to the start of cocoon spinning (day 6), whereas the decline of the 3.4 kb MG2 transcript is averted with applications up to day 7. Presented results are interpreted as showing that JH causes a “status quo” effect by preventing the disappearance of certain transcripts during molting, exerts a “juvenilizing” effect by restoring the larval pattern of splicing, and affects developmental “programming,” presumably by affecting the future pattern of gene expression. © 1996 Wiley‐Liss, Inc.

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Silk gland specific cDNAs from Galleria mellonella L.

Cited by 25 publications

References 22 publications

Identification of a Novel Type of Silk Protein and Regulation of Its Expression

Identification of a Novel Type of Silk Protein and Regulation of Its Expression

Unique Molecular Architecture of Silk Fibroin in the Waxmoth,Galleria mellonella

Juvenile hormone restores larval pattern of sericin gene transcripts

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